Abstract: Saponin is an important secondary substance stored in the rhizome of Panax japonicus var. major. According to the chemical properties of saponins, the relationships between the anatomical structure and the content of saponins in the rhizome nodes of P.japonicus var. major with different growth years were studied by means of histochemical localization, light microscope and quantitative analysis of saponins. The results showed that the cross-section of rhizome node which has two or more vascular cylinders is much complicated in structure, belongs to abnormal structural; The continual thickening growth of rhizome’s node principally resulted from the differentiation and development of the secondary and tertiary structure. The secretory cells around the cavities, secondary phloem and tertiary phloem are the main stored place of saponins in rhizome node. The numbers of secretory cavities and abnormal vascular cylinders, and saponins content increase as it grows with age. The number of secretory cavities, quantity of the abnormal vascular cylinders and density of nodes are the main structural and morphological indicators in variety breeding of P.japonicus var. major.

Key words: Panax japonicus var. major, rhizome, histochemical localization, anatomy structure, saponins contents